https://earthsky.org
Sustainability
· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
76
GRADE
C
FIX
2
REVIEW
1
PASS
3
INFO
0
Checks
63 PASS 1 REVIEW 2 FIX
DCO2 Per Page LoadAction1.17g CO2 per viewFIX
CO2 Per Page Load
Action1.17g CO2 per view
1.17g CO2 per view
Warning::
1.17g CO2 per page view
This page transfers 5.0 MB, producing an estimated 1.17g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.03g, network 0.24g, end-user device 0.90g.
Got: 1.17g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 140.7 kg CO2/year
With 10,000 page views per month, this page would generate approximately 140.7 kg of CO2 annually — equivalent to charging 17592 smartphones.
Info::
Green hosting reduces data center emissions
1.17g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 34% of websites
Sustainable Web Design model v4 · Page size: 5.0 MB
Your site
1.17g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.03g
Network
0.24g
End-user device
0.90g
At 10,000 monthly views: Monthly: 11.7 kg · Annual: 140.7 kg · ≈ 17592 smartphone charges
DCarbon BudgetAction66th percentileFIX
Carbon Budget
Action66th percentile
66th percentile
Warning::
1.17g CO2 — above the median website (0.60g)
Heavier than an estimated 34% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 66th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
1.17g
66th percentile
Cleaner than 34% of websites
✗ Above the median website
vs Median 95% more
vs Target 135% more
BTransfer Efficiency87% efficientREVIEW
Transfer Efficiency
87% efficient
87% efficient
Info::
Transfer efficiency: 87%
An estimated 656 KB (13%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 656 KB of unused JavaScript. This wasted data produces 0.15g of unnecessary CO2 per page view.
Total waste: 656 KB (13% of page weight)
Unused JS 656 KB
0.15g unnecessary CO2 per visit
Actual transfer 5074 KB
Theoretical minimum 4417 KB
Potential savings 656 KB (0.15g CO2)
See Deep Analysis sections above for specific optimizations.
A+Green HostingGreen (both)PASS
Green Hosting
Green (both)
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Cloudflare, CDN: Cloudflare
Info::
Cloudflare: Verified by the Green Web Foundation
Info::
Cloudflare: 100% renewable energy for global network since 2019
Info::
Green hosting status based on known provider commitments
Green hosting detection uses a curated database of provider renewable energy commitments. This is not a real-time verification. For authoritative checks, visit thegreenwebfoundation.org.
Green Hosting✓ Green Hosted
Hosting Cloudflare✓CDN Cloudflare✓
Cloudflare: Verified by the Green Web Foundation
Cloudflare: 100% renewable energy for global network since 2019
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight99% cachedPASS
Repeat Visit Weight
99% cached
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 33 KB (vs 5074 KB first visit). 131 of 133 resources are served from browser cache, saving 1.17g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 1.17g)
First visit
5074 KB
Repeat visit
33 KB
99% reduction on repeat visits
Saving 1.17g CO2 per returning visitor
131 resources served from cache · 2 resources re-downloaded
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
Whether the site is served from green-energy infrastructure
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.